Crenoicus harrisoni

Crenoicus harrisoni is currently only known to inhabit a spring flowing into Saxby’s Swamp in the Barrington Tops wilderness area, where it lives among the roots of mosses and other plants. Detailed surveys of aquatic crustaceans in the Mt Royal and Barrington Tops region have not found any examples of the species outside this site.

Crenoicus harrisoni is listed as a protected species in NSW under the Fisheries Management Act 1994. Heavy penalties apply for taking or possessing them.

Crenoicus harrisoni


Crenoicus harrisoni is a small, aquatic isopod crustacean measuring 9–10 mm in length. It is grey and brown with light-coloured legs. Both adults and young are blind, cannot swim and are generally slow moving, especially during the cold season. They have bright white patches on their head where their eyes should be.

Crenoicus harrisoni are relatively abundant in the particular spring where they occur, reaching densities of approximately 10–100 per square metre.

Habitat and ecology

  • Populations of species in the genus Crenoicus breed continuously, with a peak of offspring appearing during spring and a possible slowdown during the winter.
  • Young are brooded in a pouch and are released as small adults (but lacking the last walking leg).
  • Individuals are largely sedentary, living among the roots of mosses and other plants in the silty gravel substrates of springs or swamps.
  • This species does not have a dispersal stage, and as a result can only be found within a small area.
  • Why are Crenoicus harrisoni protected?

  • The species has a highly restricted distribution and therefore any disturbance could have significant and long-term impacts.
  • Although the spring flowing into Saxby’s Swamp is within the Barrington Tops National Park, impacts from human water use at this site such as for camping or day visitation could cause irreparable damage to the spring and eventual extinction of this species.
  • What conservation actions are underway?

  • Cooperation between NSW Department of Primary Industries and the NSW National Parks and Wildlife Service to ensure the protection of Crenoicus harrisoni and its habitat.

Legal implications

Taking or possessing Crenoicus harrisoni is an offence and heavy penalties apply. For corporations these penalties can include fines of up to $55 000 while individuals can face fines of up to $11 000 and up to 3 months in prison.

Bibliography and further reading

Adlem LT 1996, ‘Biogeography of the freshwater Peracarida (Crustacea) from Barrington Tops, NSW’, Bachelor of Science unpublished Honours Thesis, Dept of Geography, University of Newcastle, 97 pp.

Chilton C 1917, ‘Some Amphipoda and Isopoda from Barrington Tops (4600 ft alt.) NSW’, Journal of Proceedings of the Royal Society of New South Wales, 50, 82–98.

Nicholls GE 1944, ‘The Phreatoicoidea. Part II. The Phreatoicoidae’, Papers and Proceedings of the Royal Society of Tasmania 1943, 1–156.

Sayce OA 1900, ‘Phreatoicus shephardi—a new species of fresh-water Isopoda from Victoria’, Proceedings of the Royal Society of Victoria, n.s. 13, 25–8. (pl. 3).

Wilson GDF & Ho EL 1996, ‘Crenoicus nicholls, 1944, (Crustacea, Isopoda, Phreatoicidea): Systematics and biology of a new species from New South Wales’, Records of the Australian Museum 48, 7–32.

For further information

For more information on general fishing regulations check with your local fisheries office or visit

To contact your local NSW DPI Fisheries Office visit or phone 1300 550 474.